The Gumbel mixed model for flood frequency analysis

Many hydrological engineering planning, design, and management problems req uire a derailed knowledge of flood event characteristics, such as flood pea k, volume and duration. Flood frequency analysis often focuses on flood pea k values, and hence, provides a limited assessment of flood events. This pa per proposes the use of the Gumbel mixed model, the bivariate extreme value distribution model with Gumbel marginals, to analyze the joint probability distribution of correlated hood peaks and volumes, and the joint probabili ty distribution of correlated hood volumes and durations. Based on the marg inal distributions of these random variables, the joint distributions, the conditional probability functions, and the associated return periods are de rived. The model is tested and validated using observed flood data from the Ashuapmushuan river basin in the province of Quebec, Canada. Results indic ate that the model is suitable for representing the joint distributions of hood peaks and volumes, as well as flood volumes and durations. (C) 1999 El sevier Science B.V. All rights reserved.